Our previous applications and provisional applications, including, but not limited to, U.S. patent application Ser. No. 12/018,069, filed Jan. 22, 2008, entitled “Wireless Apparatus and Methods”, and U.S. patent application Ser. No. 12/398,179, filed Mar. 4, 2009 entitled “Packaging and Details of a Wireless power device”, the disclosures of which is herewith incorporated by reference, describe wireless transfer of power.
The transmit and receiving antennas are preferably resonant antennas, which are substantially resonant, e.g., within 10% of resonance, 15% of resonance, or 20% of resonance. The antenna is preferably of a small size to allow it to fit into a mobile, handheld device where the available space for the antenna may be limited. An embodiment describes a high efficiency antenna for the specific characteristics and environment for the power being transmitted and received.
One embodiment uses an efficient power transfer between two antennas by storing energy in the near field of the transmitting antenna, rather than sending the energy into free space in the form of a travelling electromagnetic wave. This embodiment increases the quality factor (Q) of the antennas. This can reduce radiation resistance (Rr) and loss resistance (Rl).
Our previous disclosures described different ways in which this can be done.
There are a number of different reasons why one might want to use wireless power for portable items. Wireless power avoids the tangle and clutter of wires. It also can allow the automatic recharge of a rechargeable system. Computer systems have used wireless keyboards and mice, to avoid the clutter of wires on a user's desk. However, users still need to occasionally change the batteries in such devices. The changing of batteries can be disruptive, and inconvenient.